The Beaver CNC HDZ Lives!


(Luke) #202

A little lubricant on the ball screw and blocks always helps. Other than that it’s pretty self serving


(Griff ) #203

I was never able to open it, just tried again. Set up a new project. Could not import the file. File downloaded from your site has no file type associated. It shows up as an empty box in Fusion uploads.


(Luke) #204

Before you import it add the f3d extension. Just tried it all works


(Griff ) #205

Ok

Next question, how did you save it? To your local machine or?


(Luke) #206

Yep on the mac…


(Alex) #207

Luke, how much taller is HDZ compared with the stock assembly? I thought I saw the info somewhere , but can’t find it and I need to upgrade my enclosure.
cheers, Alex


(Luke) #208

Hey,

You need approx 270mm clearance from the top of your X rail.

Ta,

Luke


(Mark Gunning) #209

Hi, I’ve discovered the woeful inadequacy of the shapeoko z axis with a 2.2kw spindle. The x and y seem to be doing alright, but they don’t have to lift the spindle weight in the same way… I saw your HDZ ballscrew actuator while fishing around for a solution. I’ve been thinking a bit about it, and I wonder if anyone can tell me why I shouldn’t try something along these lines? Please bear in mind this a very quick thrown together model to demonstrate what’s in my head…

Advantages over conventional ballscrew mounting are:

  • useable cutting travel all the way down. This drawing shows 300mm of travel
  • better shielding of the sensitive parts of the Z axis from the mess produced by cnc routing. You could even put bellows on to cover the gaps above and below the X axis extrusion.
  • good stiffness at short cutting heights - where the work is close to the x axis.

Problems:

  • worse stiffness when cutter is far from the x axis through torquing the x axis extrusion. Could it be lessened by an angle iron screwed to the x axis extrusion or a second box extrusion?
  • motor has to lift itself and the weight of the ballscrew linear actuator and the spindle and do several kilos of cutting… I see many ballscrew kits with 50kg lifting capability for a z load. I think all of this is maybe 15kg estimate?? So seems do-able?
  • would the shapeoko’s delrin v-wheels be up to dealing with this sort of weight hanging off them? (I guess so? the HDZ is not very different, and apparently that works)
  • not really a problem, but the z direction would be reversed. clockwise rotation would bring the spindle up… That’s a simple grbl fix I think? Also the z limit switch would need to point down to stop the spindle side frame as it comes up.

What do you think? Are the physics of a ballscrew linear actuator holding a spindle pretty similar whichever way round you have it? The rub comes if you do a long extension like I drew… But that’s down to the torquing that happens due to the cutter load hanging off an increasingly long lever… Stiffen the X axis extrusion or take increasingly light cuts as you move down could solve this?

I drew this using a shapeoko model I found on the sketchup 3dwarehouse. Mine is an XXL and has the new z plate (although that would be irrelevant in this scenario) The XXL would be the worst model for handling the torquing issue…

Again, your thoughts?